Need help ID'ing Pistons

[Tmwoodall]

I am trying to figure out if the PO was shooting me straight, or if I should just start totally over on this engine. These are supposedly TRW pistons. THe only markings I can find say U.S.A, and on the I believe 42 31P on the inner wall where it mounts to the arm. Nothing besides the .030 stamping on the top. I had this running years ago on the stand but decided to put a better breathing Edelbrock top end on it. So I'd really prefer to not pull them out, hence the cramped photographing area.

Any help? I was hoping to find a casting number so I could easily determine my compression ratio. Any and all help would be greatly appreciated.

[wilbilt]

That looks like a flat top "eyebrow" piston. It also looks like the valves have made contact with it (!) ?

[Tmwoodall]

Originally Posted by wilbilt

It also looks like the valves have made contact with it (!) ?

I assume you mean because the edges of the dishing on the "eyebrows" look rough? I think that is just a combo of poor picture quality, and where I wiped them down looking for any casting numbers.

[Tmwoodall]

Here we are, cleaned up a bit.

[indianbullet]

I would guess a SilvOlite cast piston not a forged TRW that I have ever seen but thats just this reporters opinion..

[chevybuldr]

Those are cast low compression pistons. the first pucture you showed the valves have made contact with the piston. They might be federal mogel not sure though. Pop one out and look at near the piston pin or inside on the skirt.

[Tmwoodall]

Help me out here, I am new to being inside a block why are you guys saying it looks like contact was made? Here is that same piston cleaned up, I see no difference between it and any of the others.

I have never been anywhere near this close to the guts, so I didn't realize it was so easy to just pop out the piston. I spent close to an hour with my video scope straining my neck and eyes, and googling at random.

Chevybuldr you are the winner, FedMogul 423NP. Arh, another lie from the PO.

[chevybuldr]

By the looks of your first picture looks like there are marks are on the valve reliefs. Now the question is what heads were on the motor? Small chamber or big chamber?

[Tmwoodall]

Originally Posted by chevybuldr

By the looks of your first picture looks like there are marks are on the valve reliefs. Now the question is what heads were on the motor? Small chamber or big chamber?

I am 99% sure what you guys are seeIng is simply where I wiped off some of the carbon deposits and it settled on the reliefs looking like a hit. The piston shown in the fist post is the same one in my last post above.

882 heads originally.
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